Process for the manufacture of solid bodies from powder.



STATES PATENT OFFICE.

*msmmcn LEISEB, or cnnnno'r'rmnne, mm, Gasman.

:20. all it may concern 'Be it known that 1,. Dr. Hammer! Lmsnn,

r; powder, and moreparticularly from fiwders .of theheavy :metals .and metals ving a'high-melting-point.. to my invention even powders .oithe .metals having the highest melting points, ;sx 1 ch;fas forinstance tungsten or which meltfar above 2500 de- (1., be vzformied into shapes of any eserirption atdow costs and at commercial temperatureathat is to say,- in a gas furnace, without. having recourse to extraordi nary heating means such as theelectric are. Heretofore. has beenproposed to make solidshapes from metallic powders by subjecting pure c stalline metal powder or pure now-crystal inc metal. powder (such, as amorphous or colloidal. metal .owder). to heavy pressure in a mold and eating the .moldedaslmpe. to a tem erature approaching the me r1point of the constituents of the mixture; a ese processes have proved to t on. accounti of {the thigh .te auresrnqecessary in or or o o tam bodies, and further on accolrr'gifiinf the apparent impossibility of obta" gat' such temperatures shapes of preconfiguration, the metal or metals when heated tonear the melting point shrinkingto such an extent that the heated "shape willtake up much less room than before and willmoreover show a great manner-mas and fissures, which tend tqmake itunsuited for further use.

According' to another method plastic masses-containing the metal 'in a colloidal state, have been subjected (either alone or mixed. with powders of other metals) to hi h. and in order to convert the co oi al' metl intorthe crystalloidal state,

- specification 0! Letters Patent.

Applicatlonfled September 27, 1812., Serial Re. 722,564.

' 'rlocnss res. rim MANUFACTURE or sonnnomns mu rownan Patented June 1, 1915.

the molded mass has then been heated to atemperature corresponding to the melting point, for instance by passing an electric current through the mass. With this method also a shrinkage of the shapes obtained is unavoidable; moreover this method is limited to the use of peptisated colloidal metals, which can only be obtained at high costs, andthe temperature applied, in the case of metals having a high melting point, is not commercial.

I have now ascertained that the conversion of the ordinary amorphous metal powders, into the crystalline modification takes place at a temperature far below the melting point of the metals employed and in almostall cases at a temperature below one half of the melting temperature. Thus the temperature of conversion of amorphous tun ten into crystalline tungsten takes place at etween 1100 and 1400 degrees 0., the melting point of tungsten bein somewhere between 2900 and 3000 degrees The temperature of conversion of amorphous iron i-nto crystalline iron is about 500 degrees 0., the melting temperature of iron being above 1200 degrees C.

I have further ascertained that the ordinary amorphous metals while being converted into crystalline metals exert a re-' markable binding effect upon any crystals of the same or any other metal which may be present. It is well known, that c stalline powder of hard metals, even if sub ected to high pressure, has no cohesion of its own and, in order to obtain shapes from such crystalline powder, either some softer metal must be admixed to 11;, to act as a binding medium, or the compressed powder must be sintered at a temperature approaching its meltin point. It is further known that if amorp ous metal powder is subjected to high ressure and heated so as to convert 1t into rystalline metal, the compressed shape will shrink enormously during the heating andlthe body obtained will show a great nu r of cracks and fissures.

A ording to my invention however, if crystalline metal powder, such as for instance crystalline tungsten powder, is mixed with some of the ordinary amo hous powder, and this mixture is then sub ected to heavy pressure and heated to convert the ordinary amorphous metal into crystalline metal, then the non-crystalline particles in being aggregated to form fresh crystals will bind together the crystalline particles already present in the mixture with such force that the body obtained after heating will show a comparatively high mechanical resistance. I

As the conversion of the amorphous metal into the crystalline metal takes place even at comparatively low temperatures, the shapes obtained at such low temperatures will not shrink at all, but will, after heating, completely fill the mold in which the ori inal mixture had been compressed.-

s the amorphous powder in being converted into the crystalline state undergoes a considerable contraction in this sense that a number of amorphous particles combine to form a crystal, a shape containing a great percentage of non-crystalline metal will after heating be more or less porous. Therefore, in order to produce dense products, the crystalline powder must by far pre- 7 vail'in the mixture, and in order to produce a product absolutely void of pores, 95 to 98 per cent. of crystalline powder and only 2 to 5 per cent. of amorphous powder must be used.

For some purposes metallic bodies having a great porosity are required, such as for instance for use as contact bodies for catalytical processes. According to my process it is easy to make such bodles by molding and heating a mixture of crystalline powder and amorphous powder, in which the latter is present to the extent of 10 to 20 er cent. By compressing and heating a mlxture of less than 80 per cent. of crystalline iron powder and more than 20 per cent. of

amorphous iron powder, iron shapes can be produced, which on account of their reduced specific gravity can advantageously be used for lifting magnets.

According to one modification of my process 4 to 8 per cent. of amorphous metal powder are suspended in water and 92 to 96 per cent. or crystalline metal powder are added. After stirring the mixture and allowing the metal to settle, the amorphous metal is deposited upon and between the crystalline particles, so that by this method an intimate mixture of the crystallinev and amorphous metals can be obtained. The liquid is then removed in any convenient manner and the dry metallic residue is molded by pressure and heated to convert the. amorphous metal into crystalline metal.

0 term amorphous metal as used in this specification and in theclaims is meant to designate the ordinary dry non-crystalline metal in contradistinction to the so-called colloidal modifications, which, as a rule, contain water more or less firmly bound.

I claim: 1

1. The process for making solid sha es from metal powders, which consists in mol ing a mixture of crystalline and amorphous metal powder, in which the crystalline metal predominates, and heating the molded mixture to convert the amorphous metal into crystalline metal.

2. The process for making solid metallic shapes which consists in preparing a mixture of crystalline and amorphous metal or metals in powder form, the crystalline metal predominating, subjecting said "mixture to pressure in a mold and heating it to convert the amorphous metal into crystalline metal.

3. The process for making solid sha es from metals having a high melting point, which consists in preparing a mixture of crystalline and amorphous powders of the said metal or metals, the crystalline powder predominating in the mixture, subjecting said mixture to heavy pressure in a mold, and heating the pressed mixture to convert the amorphous metal into crystalline metal.

4. The process for making solid metallic shapes which consists in preparing a mixture of crystalline and amorphous metal or metals, more than 80'per cent. of the mixture being crystalline metal, subjecting said mixture to heavy ressure in a 11101 and heating the presse mixture to convert the amorphous metal into crystalline metal.

5. The process for making solid metallic shapes which consists in heating a compressed mixture of more than 90 per cent. of crystalline metal powder and less than 10 per cent. of amorphous metal powder to con vert the amorphous metal into crystalline metal. I

6. The process for making solid shapes from tungsten powder which consists in subjecting to pressure in a mold a mixture of crystalline tungsten powder and amorphous tungsten powder, the crystalline tungsten predominating, and heating the compressed mixture to convert the amorphous tungsten into crystalline tungsten.

7. The process for making solid metallic shapes wh ch consists in subjecting to heavy pressure a mixture of crystalline metal powder and-amorphous metal powder, the crystalline metal predominating, and heating the compressed mixture at a temperature at which its amorphous constituent is convert ed into crystalline metal.

8. The process for making solid shapes from tungsten powder. which consists in sub jecting to pressure in a mold a mixture of crystalline tungsten powder and amorphous tungsten powder, the crystalline predominating, and heating the compressed mixture at the metallic residue by pressure and heating less than 2000 degrees C. to convert the amorphous metal into crys- 9. The process for making solid metallic talline metal. shapes which consists in suspending amor- DR. HEINRICH LETSEH. 5 pbous metal powder in a liquid, adding Witnesses:

thereto crystalline metal powder, stirring WOLDEMAR HAUPT,

the mixture, removing the liquid, molding HENRY HASPER. 

